The staff member provided video footage he took on the night which purportedly showed staff and guests partying on the stage catwalk to Bee Gee's Staying Alive as other working staff cleared up and stacked chairs.

Transcripts were, however, released following the tabling of the committee's recommendations that the government abandon its plans and build a new museum for western Sydney.

Witness "C" said he saw people tap a substance on their hand and "sniff it up". "That is definitely not any sort of cold or flu tablets I have ever seen," the witness said.

The new evidence echoed claims made in Parliament by the committee's chair Robert Borsak last year that several prominent museum staff were discovered "intoxicated, drinking Moet & Chandon in the presence of a white powder".

A still from the video showing guests dancing on night of the Powerhouse Museum's Fashion Ball.

Reading this evidence it was inconceivable that the government "would give this mob a $1.5 billion museum project, let alone responsibility for moving the collection", said former trustee Kylie Winkworth, an opponent of the move to Parramatta. "It's just shocking to see a great public museum treated like a party place for drunken antics."

Mr Borsak was critical of the lack of control and oversight at the museum at a time when it is to be relocated to Parramatta at a capital cost of $1.1 billion.

Witness B, a former senior manager, testified that the museum had been hollowed out by careerists from art institutions with no interest in protecting the institution or its prized collection.

Senior managers were either privately opposed to the relocation or were going along with the government's decision to further their careers because it might look good on their CV.

The witness said the museum had lost its way, core audiences of family, schools and older visitors had been mostly neglected, long term and dedicated professional staff and curators ignored and scorned. Social history had been removed as a priority. "They said it was boring and that it did not bring people in," the witness said.

The Fashion ball, pitched as Sydney's answer to the Met Ball, cost $388,000, of which taxpayers were billed $215,000, and raised a mere $78,000 in seed funding for the Australian Fashion Fund.

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Witness C said fundraising at the ball was a low priority. He overheard former foreign affairs minister Julie Bishop, a guest, asking, "Who do you want me to talk to?" "They shrugged and said, 'I do not know', " the witness said. "They had no game plan of what she was there for."

Later that night, he saw people that had been dancing "migrate" to upstairs offices with bottles of champagne and vodka. Later, he recalled carrying one drunken executive manager to a taxi where he propped her up on a chair because some taxis refused to take her.

In November 2018 museum trust chairman Prof Barney Glover said he was "deeply disappointed" that staff had stayed excessively, in his view, after the event in the museum. He had been assured that HR policies would be looked at and "disciplinary action is taken if necessary".